In swimming pools and spas, safety vacuum release systems (SVRS) have been developed for the removal of suction in a line of the circulation system between the pump and a blocked outlet. SVRS devices can shut down the pump when a blockage is detected at a pool drain and the suction side of the pump in order to relieve suction and prevent body entrapment. If a check valve is installed on a discharge side of the circulation system, for example to prevent the backflow of water, it can also prevent or slow the relief of the suction. As a result, vacuum forces, such as those entrapping a swimmer against a drain of the swimming pool, may remain in place longer than current standards allow. In some swimming pools, the presence of a check valve can render an SVRS device ineffective.